|
OK Perth folks! Who can offer to have a look at skygawker's scope?
50% (linearly) of the field sharp is not too much to ask. This is very eyepiece dependent, however.
The contact idea is good for a compression ring, may not be as good for set screws - but you can try.
Perhaps an investment in a Bintel Crayford focusser? Get the 10:1 fine focus version.
Interesting that you are not seeing all your primary. I'm not sure how much we get from the outer cm of the primary anyway? I read about turned down edges etc., so perhaps the edge of the mirror can be a source of optical problems - best if you don't collect light from it? Still that's just a bit of light lost - won't affect the sharpness of the image.
Yes, seeing is seldom good enough to see the textbook concentric rings. Perhaps only the innermost couple are stable. But are the spiky rings concentric, as best as you can see?
|